By Kamakshi Tandon

"Double fault-itis." Anna Kournikova went through it. Elena Dementieva went through it –still does, occasionally. And now it looks like the blonde Russian genes might be kicking in for Maria Sharapova as well.

For most of her career, she looked like an exception to that rule. Her serve was one of the strongest parts of her game, and one of the better deliveries in women's tennis at a time when many players count their return as a more powerful weapon.

But Sharapova’s serving has looked suspect a number of times this season, and she hit 13 double faults on her way to a 4-6, 7-5, 6-1 loss to Vera Zvonareva in Indian Wells on Tuesday.

“Still felt pretty rusty,” said Sharapova, who has not played since Tokyo in February because of a hamstring problem. “It’s hard to come into an event when you haven’t played a lot.”

Sharapova, who also pleaded illness after missing her post-match press conference last Friday (more details), said she was "close" to 100 percent physically and "not giving any excuses."

The loss means that Sharapova, the defending champion and top seed here, will lose her No. 1 ranking to Justine Henin next week, though the stage is set for the top spot to bounce back and forth between those two – and perhaps Amelie Mauresmo – for much of this year.

For the tournament, it’s the second biggest upset so far. The event also lost men’s defending champion and top seed Roger Federer on Sunday, the first match Federer has lost since last August.

Sharapova said she was surprised by Federer’s loss – “who wasn’t?” – but must have been equally caught off guard by her own. She was up 5-3 in the second set and served for the match before unraveling to lose 10 of the last 11 games.

Though Federer observed that the unforced error statistics have been ungenerous this past week, today’s count of 47 for Sharapova was indicative of her erratic performance during the second half of the match.

“Even in the first two sets I didn’t feel like I was playing amazing tennis, but I did the things that I needed to do,” said Sharapova. “In serving for the match, the only unforced error I really made was that swing volley.

“And after that I just deflated a bit.”

Sharapova was broken when serving for the match at 5-4 and then served three double faults in her next service game to lose the set 7-5. She showed flashes of her trademark competitiveness to get one break back in the third and fight off two match points, but played poorly on her own service games.

She was composed and pleasant when speaking to reporters afterwards, but shook off queries about her serve. “There was a lot of wrong things going on today. That was just one of them, especially in the third set,” she said. “It was more of a snowball effect than anything.”

That snowball gathered pace quickly in the third set, with Zvonareva able to succeed simply by getting the ball back deep and waiting for Sharapova’s errors, which came off both wings as well as at net – the bottom of the net, in the case of one botched volley.

But increasing hesitation about her second delivery helped set things rolling, and after winning 10 of her first 23 second serve points, she won just two of the last 16.

While Sharapova was inclined to describe the performance as just a bad day, a pattern seems to be emerging. In her last five completed matches, this is the fourth time Sharapova has hit double digits in double faults. She served 10 in a scratchy opening win against Michaella Krajicek here. In Tokyo, she hit 17 and 14 respectively in her first two matches before retiring in the semifinal against Ana Ivanovic.

Double faults also plagued her during the late stages of her last two matches at the Australian Open, where she reached the final before losing to Serena Williams in a surprisingly one-sided encounter.

It’s still a long way from the crippling problems Kournikova or Dementieva suffered – Kournikova hit 91 double faults in her first four matches in 1999 and Dementieva hit 57 on her way to the Miami final in 2004 – but still enough to put Sharapova’s serve on the watch list in Miami next week.

For Zvonareva, it’s her best win in some years. After reaching the top 10 in 2004, she suffered some assorted injuries and struggled to contain her emotions on court, sometimes breaking into tears during matches. “It was a hard time,” she said. “I’m a little bit different player [now]. I’m more mature.”

She quietly began winning matches again last summer and made a fast start in 2007 by reaching the final in Auckland and the fourth round of the Australian Open, where she fell to Sharapova in two tough sets.

Zvonareva also had her share of double faults in Tuesday’s match – remember, she’s a blonde Russian too – but once back in the match, she looked truly shaky only when trying to serve it out at 5-1.

Both players called their coaches for a courtside discussion between sets as part of the WTA Tour’s ongoing experiment with on-court coaching. “It’s really great when you have someone who understands you and give you advice and just give you support,” said Zvonareva.

Sharapova doesn’t like the idea of on-court coaching but if  “it’s there, you know – use it.”

With Martina Hingis also falling 6-4, 6-3 to Daniela Hantuchova in a repeat of the 2002 final and Jelena Jankovic going down 6-3, 7-6(1) to Na Li, the top half of the women’s draw is now as wide open as the men’s. Hantuchova will face Sharar Peer and Zvonareva will take on Li in the quarterfinals, and one of the four will eventually be going on as a surprise finalist.